37597-46-9Relevant articles and documents
NEW GENERAL AND CONVENIENT SOURCES OF ALKYL RADICALS, USEFUL FOR SELECTIVE SYNTHESES
Fontana, Francesca,Minisci, Francesco,Vismara, Elena
, p. 1975 - 1978 (1988)
Alkyl radicals are obtained from alkyl iodides under very simple conditions and with cheap reagents: i) H2O2 and DMSO; ii) H2O2 and acetone; iii) t-BuOOH.The alkyl radicals can be utilized for selective syntheses, mainly selective formation of carbon-carb
Radical chain monoalkylation of pyridines
Dénès, Fabrice,Jangra, Harish,Meléndez, Camilo,Mulliri, Kleni,Renaud, Philippe,Rieder, Samuel,Zipse, Hendrik
, p. 15362 - 15373 (2021/12/14)
The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and no external oxidant is required. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M-1 s-1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radicals to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction has been used for the preparation of unique pyridinylated terpenoids and was extended to a three-component carbopyridinylation of electron-rich alkenes including enol esters, enol ethers and enamides.
C-H alkylation of heteroarenes with alkyl oxalates by molecular photoelectrocatalysis
Xu, Fan,Lai, Xiao-Li,Xu, Hai-Chao
, p. 369 - 372 (2020/12/07)
An oxidant- and metal-free photoelectrocatalytic C-H alkylation reaction of heteroarenes with alkyl oxalates has been developed. Several classes of heteroaromatics, such as quinolines, isoquinolines, pyridines, and phenanthridines, can be alkylated with t
A General Organocatalytic System for Electron Donor-Acceptor Complex Photoactivation and Its Use in Radical Processes
De Pedro Beato, Eduardo,Melchiorre, Paolo,Spinnato, Davide,Zhou, Wei
supporting information, p. 12304 - 12314 (2021/08/20)
We report herein a modular class of organic catalysts that, acting as donors, can readily form photoactive electron donor-acceptor (EDA) complexes with a variety of radical precursors. Excitation with visible light generates open-shell intermediates under mild conditions, including nonstabilized carbon radicals and nitrogen-centered radicals. The modular nature of the commercially available xanthogenate and dithiocarbamate anion organocatalysts offers a versatile EDA complex catalytic platform for developing mechanistically distinct radical reactions, encompassing redox-neutral and net-reductive processes. Mechanistic investigations, by means of quantum yield determination, established that a closed catalytic cycle is operational for all of the developed radical processes, highlighting the ability of the organic catalysts to turn over and iteratively drive every catalytic cycle. We also demonstrate how the catalysts' stability and the method's high functional group tolerance could be advantageous for the direct radical functionalization of abundant functional groups, including aliphatic carboxylic acids and amines, and for applications in the late-stage elaboration of biorelevant compounds and enantioselective radical catalysis.
Cross-Dehydrogenative Coupling of Strong C(sp3)-H with N-Heteroarenes through Visible-Light-Induced Energy Transfer
An, Guanghui,Li, Guangming,Tian, Chao,Tian, Haitao,Yang, Hui
supporting information, p. 7709 - 7715 (2020/10/09)
The sustainable cross-dehydrogenative coupling of strong C(sp3)-H with N-heteroarenes has been developed using an efficient organic photocatalyst. It features atomic- and step-economy, and acid-free conditions. Mechanism studies suggest a previous elusive
Scalable Photoelectrochemical Dehydrogenative Cross-Coupling of Heteroarenes with Aliphatic C?H Bonds
Chen, Peng-Yu,Xu, Hai-Chao,Xu, Pin
supporting information, p. 14275 - 14280 (2020/07/13)
Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross-coupling of heteroarenes with aliphatic C?H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross-coupling of heteroarenes and C(sp3)?H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)?H donor is converted to a nucleophilic carbon radical through H-atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl?. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products.
Terminal-oxidant-free photocatalytic C-H alkylations of heteroarenes with alkylsilicates as alkyl radical precursors
Ikarashi, Gun,Morofuji, Tatsuya,Kano, Naokazu
, p. 10006 - 10009 (2020/09/23)
We report the photocatalytic C-H alkylations of heteroarenes with alkylsilicates bearing C,O-bidentate ligands under acidic conditions. Irradiation of heteroaromatics in the presence of the silicates and trifluoroacetic acid produced the corresponding alkylated compounds. The present reaction system does not require any terminal oxidant although the reaction seems to be a formal oxidation reaction. This study demonstrates that alkylsilicates can be used in photocatalytic radical chemistry under acidic conditions.
A Heck reaction/photochemical alkene isomerization sequence to prepare functionalized quinolines
Donohoe, Timothy J.,Hoff, Oskar,Hoffman, Jack B.,Kelly, Alex,Walker, Johannes C. L.,Werrel, Simon
, (2020/08/06)
A route to prepare functionalized quinolines based on a Heck reaction/UV-induced alkene isomerization sequence is described. The method allows for the preparation of quinolines under mild and neutral conditions and has broad functional group tolerance. Acid-sensitive functional groups that would not be tolerated under previous approaches can be included and a one-pot quinoline forming procedure is also reported.
Visible-light-induced C(sp3)-H oxidative arylation with heteroarenes
Liang, Xing-An,Niu, Linbin,Wang, Shengchun,Liu, Jiamei,Lei, Aiwen
supporting information, p. 2441 - 2444 (2019/03/26)
Considering the ubiquitous C(sp3)-H and the important value of alkylated heteroarenes, developing a universal method for C(sp3)-H arylation with heteroarenes is significant. Herein, we proposed a method where Selectfluor can promote
Visible Light-Promoted Aliphatic C-H Arylation Using Selectfluor as a Hydrogen Atom Transfer Reagent
Zhao, Hong,Jin, Jian
supporting information, p. 6179 - 6184 (2019/09/06)
A mild, practical method for direct arylation of unactivated C(sp3)-H bonds with heteroarenes has been achieved via photochemistry. Selectfluor is used as a hydrogen atom transfer reagent under visible light irradiation. A diverse range of chem
